Ineos Team UK's sensational comeback on day one of the Prada Cup has taken a sour turn - with another challenger reportedly protesting the British boat over a design technicality.
Sir Ben Ainslie's outfit stunned the America's Cup field on Friday during the first day's action by completing a staggering turnaround to bank two shock wins - topping pre-regatta favourites American Magic by a comprehensive 1m 20s, before rounding out a perfect day with a 28-second win over Italian syndicate Luna Rossa.
Less than a month ago Ineos performed disastrously in the America's Cup World Series, failing to win a race and struggling to stay on their foils in light breeze.
Yachting website Live Sail Die is reporting that Luna Rossa are protesting the Brits "for having their outhaul penetrating the sail skin on their main fairing". According to the report, this means a hole in their mainsail that is considered illegal - and is separate to earlier protests launched by the Italians "regarding backstays, substitute weights, and stickers".
The outhaul adjustment helps to control the shape of the mainsail and is restricted by complex America's Cup rules.
The Herald understands Ineos have recently fitted a new outhaul adjustment and that they may have tried to maximise the movement. It is believed it would be considered only a "minor infringement".
Live Sail Die reported that the rule was broken with Ineos' new outhaul, but there is no penalty yet as the part was passed at measurement. The website noted, however, that Ineos need to come up with a solution to fix the issue before their race tomorrow.
Italian websites La Stampa and LiveMedia24 also reported Team UK's break with the competition's regulations and that we will see a change on the Brittania boat in Saturday's racing.
"The rules of the America's Cup in this regard are very clear and precise: this modification is not allowed," LiveMedia24 reported overnight.
The report stated that Luna Rossa's protest "was accepted by the jury without reservation; from the next race Ineos Team UK will no longer be able to use it, but this does not affect the outcome of the previous races".
It is also believed Ineos Team UK earlier may have protested the non-use of Luna Rossa's running backstays - resulting in a late change for the challenger of record on Friday.
After forgoing the use of a running backstay in the America's Cup World Series, the Italians installed one for their opening race of the Prada Cup, against Ineos Team UK.
The backstay is a sail trim control that runs from the mast to the stern of the boat and affects the shape of the mainsail and headsail.
Luna Rossa were the only team not to use one during the America's Cup World Series as a way of minimising drag.
Heading into the Cup racing?
• Be aware that traffic will be busy, and parking will be very limited.
• Give yourself plenty of time and think about catching a ferry, train or bus instead.
• Make sure your AT HOP card is in your pocket. It's the best way to ride to the Cup.
• For more ways to enjoy race day, visit at.govt.nz/americascup.